If anything deserves the label film maudit, it’s The Keep, Michael Mann’s 1983 adaptation of F. Paul Wilson’s 1981 novel. A box office failure in the US, it was one of the first expensive, major studio productions to be released only on (pan&scan) video in the UK, though a (scratched) 16mm print was screened at the Gothique Film Society and the ICA in the mid-80s. A laserdisc release was at least letterboxed, but it is one of the few films of its vintage and reputation officially unreleased on DVD or Blu-ray – though it is available for streaming on Amazon instant video (US) and will receive a rare 35mm theatrical outing courtesy of Electric Sheep and Cigarette Burns at the Prince Charles Cinema in February.

Mann, who evidently had a bad experience on the rainy Welsh Romanian sets and with Paramount brass who insisted on several recuts, tends to skip from Thief to Manhunter when listing his filmography. Manhunter, also based on a major genre novel and a radical experiment in style, was also a flop on first release, but has been rehabilitated and valued as a significant, influential film. The Keep hasn’t, and the only cultural weight it seems to have is via its Tangerine Dream soundtrack. Wilson likes the film even less than Stephen King likes Stanley Kubrick’s The Shining, labelling it ‘visually intriguing, but otherwise utterly incomprehensible’. In Wilson’s short story ‘Cuts’, a novelist aggrieved at the butchery of his work by the movies uses voodoo to torment and dismember filmmaker Milo Gherl.

And yet, there’s something about The Keep which fascinates. I’ve seen it in a succession of formats, from blurry bootleg VHS to pristine print, and I find it improves, becomes more dreamlike and disturbing, with each viewing. During World War II, a detachment of German soldiers commanded by sensitive Captain Woermann (Jürgen Prochnow) occupies an ancient stone structure in Romania, only to have an age-old monster loosed from within its stone walls awaken to slaughter the storm troopers. Drawn to these events are an ambitious SS officer (Gabriel Byrne), a Jewish professor hauled out of a concentration camp (Ian McKellen) and a mysterious Highlander-type immortal warrior (Scott Glenn). Dark bargains are struck – though, as Wilson notes, the narrative collapses along with any moral certainties. It’s a film which opts to be eerie, allusive and overwhelming rather than exciting, frightening and shocking – a high-risk strategy.

With its dreamlike narrative discontinuity, archly stylised dialogue (‘All that we are is coming out in this Keep. You have scooped the many diseased psyches out of the German gutter. You have infected millions with your twisted fantasies. What are you meeting in the granite corridors of this Keep? Yourself?’) and expressionist imagery (almost entirely in black and white, except for the red of the monster’s eyes and the swastika armbands), The Keep is a worthy successor to a mode of horror, as morally unsettling as it is spiritually devastating, that threads through films like Murnau’s Nosferatu and Lewton and Robson’s Isle of the Dead.